A very high characteristic temperature of 150K (25-70°C) or 450K (25-50°C) and almost constant differential quantum efficiency operation were achieved in 1.3 μm GaInAsP/InP strained-layer quantum well lasers by the use of a novel temperature dependent reflectivity mirror composed of multiple quarter-wavelength thickness a-Si/SiOx dielectric films with quarter-wavelength shift in the centre